For fire blight management, here are a few of the most repeated tips for conventional growers, gleaned from several researchers and extension specialists at recent field days and conferences:
—Plan ahead. Before spring growth, identify susceptible varieties, blocks with precedent for the disease and the management history. Use that to prioritize chores.
—Consider fire blight management a year-round job, not a seasonal chore. Cut below known infection points in the winter when the cool weather may have slowed the progression of the pathogen. And don’t stop after harvest. Some trees get a flush of new growth after picking. Continue to cut away fire blight and consider a postharvest copper application.
—Cut past the point of visible symptoms. In young trees, cut 2 feet to 4 feet past the oozing canker. For older trees that aren’t growing as quickly, try about 18 inches. For first-year trees, it’s probably safest to remove the whole tree.
—Use antibiotics but try pairing them with an application of Actigard (acibenzolar-S-methyl), which induces the tree’s resistance to the pathogen.
—Avoid irrigating during bloom, or even before.
—Watch the Cougar Blight model, a computer-based risk assessment developed by Washington State University Extension, to guide timing.
—The verdict may still be out on this one, but consider letting the cuttings remain on the row floor to dry out before mulching them. The general advice to haul them away and burn them is great for small plots, but impractical for hundreds of acres. That’s one topic researchers have high on the to-study list.
—Research also is new on this in the Northwest, but try Apogee to slow down the shoots and harden the wood. Fire blight likes new growth.
Sources: Ken Johnson, Oregon State University; Kari Peter, Pennsylvania State University; Bob Gix, Blue Star Growers Inc.; Tianna DuPont, Washington State University; Mark LaPierre, Wilbur-Ellis Co.; and Neil Johnson, Northwest Wholesale Inc.
—by Ross Courtney